DE2616402A1 - COMPOSITE THREAD BASED ON CER AND OTHER RARE EARTH - Google Patents

Description

Dr. Hans-Heinrich Willrath d-62 Wiesbaden ι

Dr. Dieter Weber

Gustiv-rrtytag-Strasse Ϊ5

Dipl.-Phys. Klaus SeifFert 5, ^(061iI) f "»

^{r J} Telegram address: WLLPATENT

PATENTANWÄLTE Tel «, i-min

April 13, 1976

Series 2.187
Code no. 423-10

L "Air Liquide, Societe Anonyme pour I ¹ Etude et I ¹ Exploitation des Procedes Georges Claude 75, Quai d'Orsay, 75007 Paris / France

Composite feet on the basis of cerium and other rare earths

Priority: April 18, 1975 in France, note no. 75 12,060

The invention relates to a composite thread based on cerium and other rare earths intended for this purpose is to be introduced into a molten steel bath in such a way that its composition with regard to certain components

is changed to a weak content with regard to the partial change in the metal end properties, and in particular

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Postsdieck: Frankfurt / Main 67 63-όΟΕ Bank: Dresdner Bank AG. Wiesbaden. Account no. 276807

ORIGINAL

2616A02

especially the impact strength properties. One knows in the Practice that the assignment of cerium and other rare earths which is now also called "mischmetal", creating a complex Product is formed, which is also known under the designation "Mischmetall", in a steel melt the possibility manages to deoxidize and desulfurize the steel and thus the morphology or shapes of certain non-metallic ones To control inclusions, especially in the transfer of certain Manganese sulfides in rare earth sulfides. Even with the great chemical reactivity of cerium and the rare ones However, earths in general are very difficult to add to a molten metal bath to obtain homogeneous dilution. In the case of a normal, i.e. H. Discontinuous tapping has actually already been proposed, the cerium in the tapping pan in the form of an ingot, but this cerium block results in a more box-shaped liquid bath, and the tapping from this is consequently more difficult. It has also been proposed to introduce the cerium directly into the molds, but then the cerium is poorly distributed in the mass, and there are level deficiencies in the block base and a somewhat flawless appearance the surface.

In the case of continuous tapping, the introduction of the cerium calls either directly into the tapping pan or into it following tapping distributor the above-mentioned disadvantage that a more paste-like metal is obtained and a racking either at the level of the racking pan or

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the tapping distributor or at the level of tapping spouts becomes more difficult.

If the cerium is introduced at the level of the continuous tapping mold, it is necessary to use a continuous one Continue feeding and dose of cerium throughout the racking process. This charge cannot be in the form of a Make mixed metal thread, because it arises as a result of a violent reaction at the level of the introduction zone in the contact with the steel some difficulty in penetrating the slag. In order to gloss over this disadvantage ^ it has already been proposed to introduce this mixed metal thread into the mold, by letting it go inside a refractory tube which is immersed in the liquid metal bath; accordingly Experience shows that the refractory pipe clogs very quickly.

Whatever the ways in which a cerium thread is introduced, it should be noted that it gives a ger present in the upper flow area of the liquid metal bath, which changes the essential properties of this upper flow area, which is based on greasing and protection against oxidation. On the other hand, if the mischmetal has a relatively low melting point, of the order of 800 ^° C.-900 ^° C., it melts without penetrating into the core of the metallic mass in the melt. Its mixing is therefore not homogeneous and is essentially limited to one zone in the

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2816402

- 4 neighborhood of the surface of the metal bath.

It has been proposed i to introduce fusible or oxidizable mass into a bath of molten metal, e.g. Aluminum, magnesium or sodium, in the form of a powder which is arranged in a protective steel casing in such a way that the protective casing disappears by melting only up to a certain height above the surface of the metal bath, whereby an easier passage through the slag of the surface and melting of the meltable or oxidizable mass in the core is made possible and a homogeneous dilution is thus promoted.

It has also been proposed to use a composite in the metallic bath for deoxidizing a liquid steel To insert a thread made of an aluminum core, which is encased in a steel tube with a wall thickness of 1, 5 mm in such a way that the aluminum is covered with a steel casing melts in a zone which is arranged above the point of impact of the tapping jet. In the case of the Using a treatment of liquid steel by aluminum, a suitable distribution effect of aluminum in the in Melt located metallic mass safe.

The Effindxmgr refers to a new application and adaption

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solution of such a design for cerium, the priority exclusively is intended and adapted for the introduction of aluminum into a metallic bath.

The invention relates to a composite thread or thread . which is characterized in that the soul consists of a preformed thread made of cerium and / or other rare earths with

consists

a diameter between 1, 4 and 8,5 mn /, which is narrow from this metallic sheath is included, which has a thickness of 0.1 to 1 mm. The practical experience that it has been shown convincingly that it is easy to create such a steel casing chosen thickness to form a cerium thread, while all the previous attempts to melt the into a To pull out molten metal introduced cerium, were limited to the use of a misch metal powder, which is necessarily associated with silicon or aluminum in order to form the inner filling of a tubular steel thread. These attempts have proven to be less than fruitful, especially because the filling content (ratio between the Filling requirement unc * the total weight of the assembled Thread per unit length) is relatively light and generally cannot exceed 36% with mixed metal contents (Ratio between the weight of mischmetal and the total weight of the composite thread per unit length) of 10 to 27%, which - with regard to the compulsion, certain diameters of the thread not to exceed a light one

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Ensuring rolling and unwinding - to proceed with very fast thread insertion speeds or instead requires the simultaneous use of several introductions of thus filled tubular steel thread.

In contrast, it was no longer possible to use mischmetal as a powder, but rather a single prefabricated one Mischmetallfadens with the encapsulation technique by steel band a filling content of mischmetal and ensure a content or mischmetal content of the order of 62%.

In addition, this advantage allows the use of a previously formed misch metal thread instead of a powder on the Base of mixed metal], avoiding any noticeable Oxidation of mischmetal, which - as we know - is very eager for oxygen, and consequently the maintenance of a constant one Tension on mischmetal over the entire length of the thread covered in this way, while those filled with mischmetal powder Threads relate to very different densities due to their oxidation, which leads to the risk of breakage the wire drawing of the composite thread or wire on the one hand and a separately variable dosage of active Cer in steel in continuous tapping

Further advantages, features and possible uses of the present invention result from the following description in connection with the drawings. Show it:

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Fig. 1 shows the longitudinal view of a manufacturing plant for such a wire or thread, schematically, and

Fig. 2-6 vertical cross-sections through the wire or thread at unteischi ed borrowed points along the fabrication plant: and

Fig. 7 is a representation diagram.

In the drawings, an embodiment of a wire based on cerium, sheathed with steel _T qe is shown schematically. The production plant shown for the thread or wire based on cerium, sheathed with steel, has a steel strip bearing 1 with a strip thickness of 0.4 mm and a bearing for mixed metal wire 2 on one side. The flat steel strip 3 unwound from the magazine 1, as shown in FIG. 2, is continuously shaped by the forming rollers 4 in a channel 3, as shown in FIG. Because this channel is sufficiently curved as shown at 3- in FIG. 4, a wire made of cerium 5 with a diameter of 4 mm is unwound from the magazine 2 and inserted through a spool 6 through the passage 7, which is held by the steel band in the channel 3 " is released, after which the forming rollers 8 ensure a more and more tight wrapping of the steel band 3_, as shown in FIG. 5, until the steel band completely envelops the ceria wire 5, as shown in FIG by overlapping

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Edge to edge is done. The assembled thread or wire 9 according to Figure 6 is then drawn in 11 and onto a storage drum 10 settled. The later use of this composite wire 9 takes place by the usual unwinding and by means of wire rolls not described, which allow the direct introduction of the composite wire 9 into the bath of in Allow molten metal.

The compound wire on the basis of a Cerseele, which is sheathed with steel, can be accomplished with dimensions from 1.4 to 8.5 mm for the diameter of the ceria wire as well an envelope thickness between 0.1 and 1 mm, dimensions that result from the following statements with reference to FIG result:

1 . The diagram in FIG. 7 shows in a general manner on the ordinate the diameter d (expressed in mm) of the cerium wire core as a function of the insertion speed v, (expressed in meters per minute m / mn) of the compound Wire into the liquid metal.

For reasons of commercial practice, it is believed that the cerium wire cannot have a diameter less than 1.4 mm, for below this value, the wrapping operation causes considerable difficulties. On the other hand, one takes into account that the ceria wire cannot have a diameter of more than 8.5 mm,

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because above this diameter one encounters winding and unwinding difficulties.

In FIG. 7, these limits are in the form of two lines parallel to the abscissa or on the ordinate 1, 4 mm (d min) and on the. Ordinate 8.5 mm (d max) related.

2. The introduction speed ν (m / mn) of the assembled wire into the molten metal must itself be within certain limits be included. On the one hand it is absolutely necessary that the speed ν is greater than 3 m / mn, in order to obtain a good accuracy for the amount of ger introduced per ton of treated metal. on the other hand this speed ν must be below 30 m / mn for safety reasons and for reasons of a successful unwinding operation. These two limits are indicated by two lines parallel to the ordinate or 3 m / mn (v min) and for the abscissa shown on the abscissa 30 m / mn (v max).

3. In the course of experiments it has been found experimentally that the penetration depth (L) is related to the wire structure (the diameter d of the Cereal core and the thickness e of the envelope) and the insertion speed ν (m / mn) by the equation:

L = 1.7 each + 0.35 d | v.

10 " ²

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When you commit yourself to a depth of penetration _; one notices that a bundle of curves can be recorded in the diameter of FIG. translated.

The penetration depth L should in any case be more than 0.3 m, otherwise there is a risk that Qer will come into contact with the the slag covering the molten metal comes.

The penetration depth must be less than 1 m, otherwise the accuracy in handling the wire will be missed there is a risk of hooking himself onto a frozen wall of the steel fire. Beyond this depth one loses on the other hand, the homogeneity of the cerium distribution, because a substantial part of the steel has already solidified.

In FIG. 7, two sets of curves "d" have been shown as a function of "e". The first bundle on the left in the diagram corresponds to a minimum penetration depth L (min) of 0.3 m for steel strip thicknesses e, which fade one after the other e .. = 1. 25 mm; e, = 1 mm; e = 0.80 mm e. = 0.60 mm, e, - = 0.4 mm, e _β = 0.25 mm; e ₇ = 0.1 mm.

The second set of curves on the right in the diagram corresponds to a maximum penetration depth L (max) of 1 m for steel strip thicknesses that decrease one after the other from e '= 1.50 mm; e ¹ - = 1.25 mm, e ¹ - = 1.00 mm, e '= 0.80 mm, e' = 0.60 mm; e ¹ , = 0.40 mm; e '= 0.25 mm.

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According to what has been said above, it is found that for any given depth the innovation concerns the only curves whose thickness e is now greater than 0.1 and less than 1 mm, resulting in curves such as e * (for L min), e 'and e' (for L max) are excluded.

4. It is expedient to respect another double condition. In fact:

- on the one hand, the thickness e (mm) must be over 0.04 χ d (mm) because a thickness below this value would lead to a wire that is too brittle. In other words, for each thickness e .., e., ... e ', e ¹ -... diameter ^ maxima for cerium wires d .. (max), d ₂ (max) ... d ¹ - (max), d * 2 (max) ... determine, some of which are represented by a solid, very short line.

- On the other hand, the thickness e (mm) must be less than 0.2 d (mm), otherwise one would have a wire that is too strong, difficult to manufacture, to be rolled up and unrolled. In other words, for any thickness e * , e e'-jf e ' ₂ ··· minimum diameter for cerium wire d' (min), d_ (min) ... d '(min) d' ₂ (min). .. determine> some of which are also shown by a very short dashed line.

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The diagram according to FIG. 7 allows the appropriate wire to be determined.

The zones outside the rectangle and the hatched zones are prohibited for use.

A given steel strip thickness e has two representative curves that form a. corresponds to the maximum penetration depth (L max) of 1m, the other to a minimum depth (L min) of 0.3 mm. For each of these curves a lower mark delimits d (min), d ₂ (r? In). .. d '.. (min), d' (min) or an upper marking d .. (max) d ₂ (max) ... d '(max), d' (max) the acceptable diameter.

Usage examples:

1. If you specify a steel strip thickness of 0.4 mm (e ^ in the drawing) the diameter of the mischmetal wire can be between 2 mm (lower mark d, - (min) in the left curve bundle) and 8.5 mm (upper marking d (max) in both curve bundles).

If you now specify a diameter of 4.7 mm in this fork, the insertion speed can be between 8.8 m / mn and 28.8 m / mn, as shown on the right-hand side labeled "Example 1".

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2. If you have a feed rate of 15 m / ran and a Steel strip width of 0.25 min (e ^ in the drawing), the diameter can be between 2.7 mm, the lower mark corresponding to the minimum penetration L (min). and 6.3 mm the upper marking according to the permissible Maximum diameter d '(max) for this steel strip thickness: right

designated in the figure as "ex. 2".

3. If the diameter is, for example, 4.7 mm and the insertion speed z. B. to 15 m / mn (position A in the figure) specifies, the minimum thickness of the steel strip is 0.19 mm and the maximum thickness 0.94 mm, limits which correspond to the durability and strength of the wire.

As mentioned at the beginning, the invention is applicable to work with cast steel and in particular continuous cast steels.

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Claims (2)

Claims .- Compound wire with a core containing cerium and / or has other rare earths, inside a metallic envelope, characterized in that the soul is formed from a prefabricated wire made of cerium and / or other rare earths with a diameter d (mm), which is between 1.4 and 8.5 mm, which is tightly enclosed by this metallic envelope, which has a thickness e (mm) has, which is between 0.1 and 1 mm, with, among other things, the double condition that e (mm) on the one hand over 0.04 d (mm) and on the other hand is less than 0.2 d (mm). 2. composite wire according to claim 1, characterized in that that the envelope is a steel band enveloping the soul with overlapping of the longitudinal edges of the steel band. 609845/0700 fs Blank page